Precise in-field molecular diagnostics of crop diseases by smartphone-based mutation-resolved pathogenic RNA analysis

Molecular diagnostics for crop diseases can guide the precise application of pesticides, thereby reducing pesticide usage while improving crop yield, but tools are lacking. Here, we report an in-field molecular diagnostic tool that uses a cheap colorimetric paper and a smartphone, allowing multiplexed, low-cost, rapid detection of crop pathogens. Rapid nucleic acid amplification-free detection of pathogenic RNA is achieved by combining toehold-mediated strand displacement with a metal ion-mediated urease catalysis reaction. We demonstrate multiplexed detection of six wheat pathogenic fungi and an early detection of wheat stripe rust. When coupled with a microneedle for rapid nucleic acid extraction and a smartphone app for results analysis, the sample-to-result test can be completed in ~10 min in the field. Importantly, by detecting fungal RNA and mutations, the approach allows to distinguish viable and dead pathogens and to sensitively identify mutation-carrying fungicide-resistant isolates, providing fundamental information for precision crop disease management.


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All studies must disclose on these points even when the disclosure is negative. The study did not involve human research participants, thus not provide sex and gender information.
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Wheat leaf samples for estimating the accuracy of the colorimetric assay were randomly picked to test ( Fig. 2d and 2e). Other samples were not randomized.
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March 2021
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During February to to May 2021, wheat leaf samples were collected from fields from five provinces in in China, including Gansu, Guizhou, Qinghai, Shaanxi and Yunnan.
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